paleoanthropology2: When and where did the Homo genus first appear? (v1.0)

Key Reference are Wikipedia, and prof John Hawks of university of Wisconsin, Madison.

We humans have been looking for our origins for a long time. Where and when did the homo genus first emerge? Who are our direct ancestors?

In the 19^th and 20^th century we did not have the tools and technology like we have today to study origins – most notably accurately dating the age of fossils. A lot of false starts were made, and the search for origins spread across many areas including Europe, Africa, central Asia, and southeast and east Asia. Charles Darwin though surmised very early on in the 19^th century that we likely originated in Africa. He studied gorillas and Chimpanzees there and came to that conclusion. He was eventually proved correct but many other fossils all over the world were also studied as possible candidates of human origin. You might have heard of some of the famous ones:

• 1.     Ardi (Ardipithecus Ramidus: discovered in 1992 in Ethiopia and estimated to be 4.4 million years old)
• 2.     Lucy (AustralopIthecus afarensis: Discovered in 1974 in Ethiopia and estimated to be 3.2 million years old),
• 3.     Taung Child (AustralopIthecus Africanis: Discovered in 1924 in south africa and estimated to be 2.8 million years old),
• 4.     Turkana boy also called Nariokotome Boy (Homo Erectus Ergaster: discovered in 1984 in Kenya and estimated to be 1.6 million years old). It is the most complete Homo Erectus fossil in Africa. 
• 5.     Java Man (Homo Erectus Erectus: discovered in 1891 in Java and estimated to be 700,000 to 1490,000 years old)),
• 6.     Peking Man (Homo Erectus Pekinensis: discovered in China in 1921 and estimated to be 780,000 to 230,000 years old),
• 7.     Heidelberg man (Homo Heidelbergensis: discovered in 1907 in Germany and estimated to be 500,000 years old). Also found in a number of places in Africa and Asia. 
• 8.     many Homo Neanderthal fossils in Europe.

Hominins are any member of the zoological “tribe” Hominini (family Hominidae, Order Primates), of which only one species exists today - Homo Sapiens, or human beings. The term is used most often to refer to extinct members of the human lineage.

For the first, four million years or so of hominin evolution, the hominin fossil record is characterized by, among other trends, canine reduction and postcranial metamorphosis in the following genera: Sahelanthropus, Orrorin, Ardipithecus, Australopithecus and Paranthropus. As the Pliocene epoch (5.3 million to 2.5 million years ago) came to a close and global climate was shifting at about 2.5 million years ago, there is a concomitant change in the hominin fossil record. In this increasingly cooler world, something new, both anatomically and behaviorally, emerged. This is the origin of the genus Homo. The origin is in Africa. The current consensus of anthropologists is that the direct ancestors of modern humans were African populations of Homo Heidelbergensis.  

The origin of the genus Homo in Africa signals the beginning of the shift from increasingly bipedal apes to primitive, large-brained, stone toolmaking, meat-eaters that traveled far and wide. This early part of the homo genus is represented by three species: Homo habilis, Homo rudolfensis, and Homo erectus. H. habilis is known for retaining primitive features that link it to australopiths. Little is known about H. rudolfensis except that it had a relatively large brain and large teeth compared to H. habilis and that it overlapped in time and space with other early Homo. Our understanding of paleobiology and evolution of the larger-brained H. erectus is enhanced due to its rich fossil record. H. erectus was the first obligate, fully committed biped, and with a body adapted for modern striding locomotion, it was also the first in the human lineage to disperse outside of Africa. The early members of the genus Homo are the first to tip the scale from the more apish side of our evolutionary history toward the more human one. The oldest H Erectus fossil is about 2 million years ago discovered in East Turkana, Kenya in the 1970's. Successive waves of the Homo genus migrated out of Africa. 

H Erectus had a more modern gait and body proportions and was the first human species to have exhibited a flat face, prominent nose, and possibly sparse body hair coverage. Though the species' brain size certainly exceeds that of ancestor species, capacity varied widely depending on the population. In earlier populations, brain development seemed to cease early in childhood, suggesting that offspring were largely self-sufficient at birth, thus limiting cognitive development through life. Sites generally show consumption of medium to large animals, such as bovines and elephants, and suggest the development of predatory behavior and coordinated hunting. H. erectus is associated with the Acheulean stone tool industry and is postulated to have been the earliest human ancestor capable of using fire, hunting and gathering in coordinated groups, caring for injured or sick group members, and possibly seafaring and art (though examples of art are controversial, and are otherwise rudimentary and few and far between).